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- South African Journal of Sports Medicine
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- Volume 18, Issue 4, 2006
South African Journal of Sports Medicine - Volume 18, Issue 4, 2006
Volumes & issues
Volume 18, Issue 4, 2006
Causes of extreme fatigue in underperforming athletes - a synthesis of recent hypotheses and reviews : review articleSource: South African Journal of Sports Medicine 18, pp 108 –114 (2006)More Less
The underperformance syndrome (UPS), previously known as the overtraining syndrome (OTS), has been defined as a persistent decrement in athletic performance capacity despite 2 weeks of relative rest. Clinical research has suggested that cytokines play a key role in fatigue in disease and chronic fatigue syndrome. Furthermore, it has recently been demonstrated that exogenous administration of interleukin-6 (IL-6) increases the sensation of fatigue during exercise. In light of current cytokine and chronic fatigue syndrome research, this article reviews and updates the cytokine theories that attempt to explain the aetiology of the debilitating fatigue experienced in OTS / UPS. Initially, it was proposed that UPS may be caused by excessive cytokine release during and following exercise, causing a chronic inflammatory state and 'cytokine sickness'. More recently, the hypothesis was extended and it was proposed that time-dependent sensitisation could provide a model through which the aetiology of UPS may be explained. According to this model, the principal abnormal factor in UPS is an intolerance / heightened sensitivity to IL-6 during exercise.
The effects of exercise training in patients with peripheral vascular disease - a review : review articleSource: South African Journal of Sports Medicine 18, pp 116 –121 (2006)More Less
Patients with peripheral vascular disease (PVD) suffer from the symptom of intermittent claudication and are therefore intolerant to walking. Exercise training has been shown to be a beneficial treatment for patients with PVD. Therefore studies have aimed to assess the efficacy of exercise training programmes. This review summarises the data on the efficacy of exercise training programmes in patients with PVD. Recommendations are made for the mode, duration, frequency and intensity of exercise training programmes.
A systematic review of Medline, Pubmed and Science Direct was done of studies on exercise training and patients with PVD, particularly those using randomised controlled trials.
Exercise training improves walking tolerance in patients with PVD. The common mode of training in patients with PVD in the past decade has been walking on a treadmill; however recently an upper-limb cycle ergometry programme proved to be as effective as lower-limb cycle ergometry in improving walking tolerance in patients with PVD. As weight-bearing walking programmes are uncomfortable for patients with PVD, this is an important development in exercise prescription for these patients. Most successful exercise programmes have been 3-6 months in duration for a period of 30 minutes to 1 hour, 2-3 times per week. However, 1 study showed that a shorter period (6 weeks) was of sufficient duration to improve functional capacity in patients with PVD. This is helpful for practitioners as exercise programmes of 3 or 6 months can be daunting for a patient to embark on. Finally, patients should exercise to maximal claudication pain in order to elicit the best training response.
Mountain-bike racing - the influence of prior glycogen-reducing exercise and glutamine supplementation on selected stress and immune parameters : original research articleSource: South African Journal of Sports Medicine 18, pp 122 –128 (2006)More Less
Objective. To investigate the effect of pre-exercise glutamine supplementation and the influence of a prior acute bout of glycogen-reducing exercise on the general stress and immune response to acute high-intensity cycling.
Design. Randomised, double-blind, cross-over supplementation study.
Setting and intervention. Subjects performed a series of 4 simulated mountain-bike races lasting ≈ 60 minutes each on separate days 1 week apart, with / without prior glycogen- reducing exercise on a known outdoor course with / without pre-exercise glutamine supplementation. Blood samples were collected pre- and immediately post-exercise after each race.
Main outcome measures. Circulating concentrations of cortisol (COR) and dehydroepiandrosterone-sulphate (DHEAS) were assessed at all time points, as well as changes in white blood cell (WBC) subpopulation distribution.
Results. COR was elevated in all groups post-exercise (p < 0.0001), but neither glycogen reduction, nor glutamine supplementation had any effect. DHEAS increased post-exercise (p < 0.05), with a greater relative increase in glutamine-supplemented subjects (p = 0.07). Total WBC and neutrophil counts in all groups were elevated after exercise (both p < 0.0005). Glutamine supplementation had no effect on differential WBC counts or distribution, but total WBC (p = 0.06) and monocyte (p < 0.05) counts showed greater increases after glycogen reduction. Gluta-mine supplementation was associated with greater postexercise decreases in CD4+ count (p = 0.07) and CD4+: CD8+ ratio (p = 0.01) after glycogen-reducing exercise.
Conclusions. We conclude that pre-exercise glutamine supplementation may have an anticortisol effect by enhancing the DHEAS response to exercise stress. The suppressive effect of glutamine supplementation on CD4+: CD8+ ratio and its positive effect on monocyte count after repeated bouts of exercise warrants further investigation.
Analysis of patient load data for teams competing in the 2003 Cricket World Cup in South Africa : original research articleSource: South African Journal of Sports Medicine 18, pp 129 –134 (2006)More Less
Objectives. To evaluate the injury presentation data for all teams taking part in 10 warm-up matches and 46 matches during the 2003 Cricket World Cup played in South Africa, in order to provide organisers with the basis of a sound medical-care plan for future tournaments of a similar nature.
Methods. The data collected included the role of the injured person, the nature of the injury, whether the treatment was for an injury or an illness, whether the injury was acute, chronic or acute-on-chronic, and the prognosis (rest, play, unfit to play, sent home, follow-up treatment required). The medical personnel in charge of the medical support documented patient information which included the total number of patient presentations and the category of illness/injury.
Results. Ninety patient presentations (1.6 patient presentations per match) were recorded. The most common patient presentations were by the batsmen (50%), followed by the bowlers (29%) and all-rounders (17%). Of the patient presentations, 53% were classified as injuries, while the remaining 47% were classified as illnesses. The patient presentations occurred in the early stages of the competition. The most common presentations were of an acute nature (63%). The main injury pathology categories were trigger point injuries (10%), and bruises / abrasions (10%), while infection (29%) was the main illness pathology.
Conclusions. The 2003 Cricket World Cup proved to be an ideal opportunity to collect data on international cricketers participating in an intensive 6-week international competition; the epidemiological data collected should assist national cricket bodies and organisers of future Cricket World Cup competitions to predict participant-related injury rates.
High-intensity exercise and recovery during short-term supplementation with creatine plus a protein-carbohydrate formula : original research articleAuthor J.R. ClarkSource: South African Journal of Sports Medicine 18, pp 136 –140 (2006)More Less
Objective. To determine the effect of short-term creatine supplementation plus a protein-carbohydrate formula on high-intensity exercise performance and recovery.
Design. A repeated-measures, experimental study, employinga randomised, double-blind, placebo-controlled, group comparison design was used.
Interventions. Thirty active but not sprint-trained male subjects were randomly assigned to 1 of 3 groups: creatine plus protein-carbohydrate formula (CRF); creatine only (CRE); and control (CON). All groups were exposed to the same high-intensity sprint exercise programme, 3 times per week for 30 days.
Main outcome measures. Dependant variables included total repeat sprint distance, fatigue index, perceived muscle pain, and blood lactate, urea, creatine kinase, and cortisol concentrations.
Results. All groups significantly (p ≤ 0.05) increased total sprint distance and decreased blood urea concentrations. There were no significant changes in blood lactate or cortisol concentrations in any group. CRF showed significant decreases (p ≤ 0.05) in fatigue index, muscle pain, and creatine kinase concentration. However, no significant differences were found between groups.
Conclusion. Short-term creatine supplementation with or without protein-carbohydrate supplementation does not appear to enhance performance or recovery significantly over high-intensity exercise training alone in non-sprint-trained individuals. A longer trial period may be required to evaluate effect on recovery more conclusively. In addition, the prime importance of physical conditioning, and in particular task-specific exercise training, in stimulating performance and recovery adaptations is highlighted.